To perform navigation or provide other location based services (LBS), it is necessary to accurately determine a geographical location of a user. In recent years, many methods for determining the geographical location of the user, such as a global positioning system (GPS) positioning method and a WIFI positioning method, have been proposed. In the GPS positioning method, geographical coordinates of a portable device carried by the user are calculated and determined based on a GPS signal which is received by the portable device, so as to determine the geographical location of the user. However, the GPS positioning method is limited by a capability of receiving the GPS signal by the portable device. For example, when the portable device is located indoors, underground and at a location between buildings, it is hard for this portable device to receive a high-quality GPS signal, leading to decreased positioning accuracy or even a failure of positioning. In the WIFI positioning method, a mapping relationship between service set identifier (SSID) lists of WIFI devices provided in respective geographical locations and the respective geographical locations is stored in a database in advance. Then, at the time of positioning, a SSID list of WIFI devices at a place where the user is located is sensed, and the list is matched with the SSID lists stored in the database in advance, so as to determine the geographical location of the user according to the geographical location to which a matching SSID list is mapped. However, in the WIFI positioning method, it is required to collect the SSID lists of the respective geographical locations in advance on site, which leads to a high cost, and if the WIFI devices in some geographical location changes, the SSID list stored in the database will be outdated, causing decreased positioning accuracy and even a failure of positioning.